Indentation Size Effect

1. Fundamental Micromechanics and Materials Dynamics ofThermal Barrier Coating Systems Containing Multiple LayersMark L. Weaver, The University of Alabama Tuscaloosa, DMR Award #9984899 Indentation Size Effect Hardness tests conducted to determine mechanical properties of NiAl single crystals and NiAl bond coats applied to superalloy substrates. An indentation size effect (ISE) is observed in both systems. ISE caused by friction between the indenter and specimen surface. Lubrication of specimen removes the ISE. (Figure 1) An energy balance model predicts the “true” load independent microhardness for any material even in presence of ISE. (Table I) Important to correctly interpret the hardness results for applications to various mechanical and wear situations. u u u M.L. Weaver, M.E. Stevenson and R.C. Bradt, “Knoop Microhardness Anisotropy and the Indentation Size Effect on the (100) of Single Crystal NiAl,” in press Materials Science and Engineering A (2002). B. Ning, M.E. Stevenson, M.L. Weaver and R.C. Bradt, “Apparent Indentation Size Effect in a CVD Coated Ni-Base Superalloy,” submitted to Thin Solid Films (2002). Load dependence of Knoop microhardness

2. Fundamental Micromechanics and Materials Dynamics ofThermal Barrier Coating Systems Containing Multiple LayersMark L. Weaver, The University of Alabama Tuscaloosa, DMR Award #9984899 Training • 2 graduate students (Bo Ning and Jonathan Sullivan) have participated in research. • 3 undergraduates have worked on the physical modeling of the morphological instabilities observed at the mid-ocean ridges. • Student (Bo Ning) presented research at the 2002 International Conference on Metallurgical Coatings and Thin Films. Dr Weaver demonstrating mechanical testing to summer program participants. Outreach • Development of lectures on the mechanical properties of thin films and coatings for required course MTE 455 – Mechanical Behavior of Materials. • Introducing Science Faculty from HBCU’s to Materials Science and Engineering– Three-week workshop to introduce to introduce mathematics and science educators from HBCU’s to materials science and engineering through traditional classroom lectures, interactive laboratory activities, and site visits to national laboratories and industries involved in materials science and engineering.